Land vehicles are tested for crashworthiness by a variety of tests including frontal impacts, side impacts, rear impacts, roll-over and other tests. Frontal impact tests were previously developed that specified that a vehicle impacts a barrier between the frame rails that extend longitudinally relative to the vehicle. In this type of test, the frame rails provided the primary support for the vehicle body. The extent of any intrusions into the passenger compartment are measured at the brake pedal, foot rest, left toe pan, center toe pan, right toe pan, left instrument panel, right instrument panel, and door.
A new test is proposed for simulating small offset frontal crashes against a rigid barrier. In the proposed test, the vehicle impacts a rigid barrier having a six inch pole-like radius on one corner with a 25% overlap at 40 MPH. The impact is outboard of the frame rails and the frame rails do not provide as much resistance to intrusion into the passenger compartment as in the case of impacts between the frame rails.
The weight of land vehicles is being reduced to substantially improve fuel efficiency. Vehicles are currently being designed to reduce the weight of the vehicle with an objective of not compromising performance or crashworthiness. It is difficult to meet the proposed test requirements for the small offset rigid barrier crash test while reducing vehicle weight and reducing manufacturing costs.
Reducing the weight of vehicles is a continuing goal in vehicle design. One way to reduce the weight of a vehicle is to reduce the number of parts used to manufacture a vehicle. Some structural rails are fabricated in multiple pieces and may be complicated to fabricate and assemble. Multi-piece structural rails are higher weight, higher cost, complicated to assemble, less dimensionally accurate and are subject to assembly complexity of multiple component constructions. Multi-piece assembly processes must be carefully performed and monitored for quality control. Reduced weight of parts improves fuel economy and results in reduced material costs.
One way to reduce part count is to manufacture rails in a hydroforming process. However, hydro-formed rails are generally monolithic structures. During axial loading events, hydro-formed structures tend to first deform principally at locations on the rail that include bends in the rail. The portions of the rail that extend linearly in the longitudinal direction do not easily bend or fracture. These portions of the rails do not absorb energy in a collision event to the same extent as portions that include bends and increase the likelihood of intrusions into the passenger compartment in small offset rigid barrier tests.
This disclosure is directed to solving the above problems and other problems as summarized below.